Been a member for a few years but haven't posted in a while, hope all are doing well.

I am in need of some assistance. This morning the following lights on dash lit up. 2003 GS300 CEL/VSC/VSC-off. I pulled the code P0031 - heat oxygen sensor, heater control circuit low bank 1 sensor 1.

I read through many of the posts regarding this, searched Google and will admit i am still not 100% certain if i have the correct sensor identified. I found this picture from another post to use as a reference and would appreciate if someone can confirm that the sensor circled in the pic, is the one i need to replace or is it the one above it??

many thanks.

 

The circled look like bank 1 sensor 2. It would be before cat.

 

Thanks GSTim, so the one above not circled, got it.

Curious what does the reference to "low bank" mean? I now know it's bank 1 sensor 1, which i assume is what is also referred to as the upstream sensor, right? But what is low bank? Sorry if its a stupid question but as i have been doing more and more of my own repairs i am learning a lot.

thanks again.

 

well after letting the PB soak over night and having purchased the sensor socket i was able to remove the old sensor but it was extremely difficult even using the pry bar.

It finally came out but the thread on the sensor itself is wrapped in what i assume is the old anti-seize and the thread in the hole of bank 1 appears to have anti-seize on the threads as well and i am unable to remove it from the threads. I am now concerned that I may not be able to screw in the new sensor.

any suggestions on how to clean the threads?

Thanks!

 

Without buying the specialty tools for it, I say a wire brush and a vacuum

 

thanks. a neighbor suggested the wire brush and a pick but neither worked to remove the excess anti-seize. I tried to twist in the new sensor to see if it would go in straight but it does not and it's tough getting the threads to connect/grab. I am guessing the threads are shot. I am going to take it to a mechanic shop to finish what I started.

thanks.

 

why not buy a tap and just run the tap through the threading (should remove the anti-seize)

 

Agree 👍👍👍👍👍

 

Thanks. what looked like caked on anti-seize to me wasn't. the threads on the old sensor and inside the bung (I think this is what it's called) were trashed from the start of the thread, mid-way in the bung. The mechanic rethread the bung, new sensor is in and car back in operation.

Not sure what i did wrong with removing the old sensor and not sure if i did the damage or not. But its fixed now.

appreciate the responses.

 

I know this is an old thread that has already been resolved but I just wanted to point out that the code is for “heater circuit low bank one sensor one” meaning that the circuit voltage is low not that the bank is low so you would read it like “heater circuit low” and then “bank one sensor one”